Reinforced propeller blade



G. w. BRADY REINFORCED PROPELLER BLADE Filed Dec. 9, 1943 July 29, w47

ATTORNEY v Patented `Iuly 29, 1947 rRientroRolin lPRorELLEit BLADE George W. Brady, 'Upper MontclainN.- J., assignor to Curtiss-Wright Corporation, a corporation of Delaware Application December 9, 1943, Serial No. 513,574

This invention relates to aircraft propeller blades and more particularly to hollow propeller blades which are internally reinforced.

The invention has particular reference toa :hol-

low blade formed f-rom plates disposed in facing relation and forming an interior chamber, each plate including a longitudinally extending rib formed integrally therewith, the ribs' facing each other and being used for reinforcing .purposes as hereinafter described.

The invention has further reference to a propeller blade, .as specified, wherein a tapered connecting member bridges the space between and is connected to the aforesaid ribs.

The principal object of the invention is 'to provide a hollow, reinforced propeller .blade wherein points of weakness in either of the plates, forming the blade, are obviated.

A further object of the invention is to :provide a propeller blade, as specified, wherein a point of weakness in the rib connecting member per se, is eliminated.

Another object of the invention isto` provide a propeller blade, .as specified, wherein the plates forming the blade are strengthened in regions` where one end of an internal reinforcing member terminates.

A further object of the invention is-to provide a propeller blade, as specified, wherein an. internal bridging member is itself reinforced at one end thereof. z

Various other objects, advantages and features of my invention will become apparent from the following detailed description.

My invention resides in the reinforced hollow propeller blade, combinations and arrangements of the character hereinafter described and claimed. Y

For an understanding of the invention and for an. illustration of one of the forms thereof, reference is to be had to the accompanying drawings,

in which: y

Figure 1 is a longitudinal, vertical sectional View showing a hollow propeller blade as constructed in accordance with my invention;

Fig. 2 is an enlarged, longitudinal, vertical sectional view similar to Fig. 1;

Fig. 3 is a sectional view taken on the line 3 3 of Fig. 1;

Fig. 4 is a -similar View taken on the line 4 4 of Fig. 1; and

Fig. 5 is a fragmentary section taken on the line 5-5 of Fig. 1. l

Referring to Figs. 1A through'4, I metallic camber plate Il]A and a metallievthrust plate Il of the general character known in the art for forming a hollowpropeller blade `I-2"-. As illustrated, the camper ,plate I!! comprises a tubular shank I3 with' the plate proper extending therefrom and generally of convex configuration,

have showna Y `.a claims. (o1. 17o-15.9)

vthe Iconvexity of said plate decreasing in a progressive manner as the end thereof is approached whereby the camber plate If0 defines a shallow lopening of generally elliptical configuration.

The thrust plate I-I comprises a plate proper whichgenerlally isalso of elliptical configuration to .correspond with the aforesaid shallow opening of the -camber Iplate I- and,` to less extent than the latter, it is convex in shape. As vwill loe-noted in Fig. l, the thrust plate II does not include a shank section as does the camber plate I0,

As illustrated, the plates I0 and II, include the respective longitudinally extending integral ribs 10a and I Ia which, when said plates are assembled, are disposed substantially infacin'g'relation `or in a common plane.

As herein shown, 'althoughY not necessarily, `the ribs Illa and I la are for-med, as described in `pending application Serial No.- 493,314, filed July 2, 1943, by subjecting vuniformly thick plane sheets :of metal, which form the blank plates for the respective -camber and thrust plates I!) `and II,

herein disclosed, vto two or more milling operations, whereby each sheet of metal is longitudinal- :1y tapered in such manner that the thickness thereof decreases longitudinally` towardthe tip of the blade I2.

ln the said` tapering operation, longitudinal 'strips of the original sheets of metalV remain inta-ct, these strips of metal forming the respective ribs Illa and Ila, the ends thereof, toward the left, terminating approximately at they respective locations A, indicated in Fig. 2. Moreover, the thickness or height of each ofthe ribs `Illa or Ila increases progressively in a direction extending longitudinallyk along the propeller blade I2 toward the tip thereof.

In accordance with the present invention, the

aforesaid milling operation is carried' out in a manner whereby the ribs Illa and I1 la at the ends, toward the left, widen or spread out into the respective rectangular reinforcing pads I'5 and I6 whereby to` increase the thicknessof the plates I0 and Il for a purpose hereinafter to be described.

After the blank plates have been milled, the camber plate I0 and the thrust plate II' are brought to the finished form by subjecting each of them` to the final milling operation, andfthen trimming' andv shaping operations, the convex configurationand the twist being imparted thereto during the operation last noted, all as' genorally' referred to in said pending application.

' As known in theY art and as disclosed in pending application, SerialV No. 496,232, filedJuly 26,

0f the ribs Illa and Ila when the two plates Il)V It is a feature of the invention that I 'rein-* force the plates IB and II by providing a connecting member, lll which spans the space between the ribs Ia, lla and which is welded or otherwise suitably secured thereto. At its wide end, the connecting member I4 is provided with a recess Il which, in configuration, is approximately that of a halfcircle in contradistinction to the lengthy tapered recess of the priorart. It follows, therefore, that the depth of said recess I 1 is preferably although not necessarily equal to, the width thereof and the edge area thereof, defining said recess I1', is thickened or enlarged to form reinforcing webs or rims IB on the respective opposite sides of said connecting member Ill. i

As will readily be apparent from an inspection of Fig. 2, the connecting member AHl is positioned between and connects the ribs Illa and lla with the reinforced, recessedv end of said connecting member I 4 terminatingon the pads I5 and I6.

As noted, the recess AII is anked by thethick'- enedwebs I8 and an arrangement of this characte;- materially decreases the fracture hazard in the'connecting member at the recessed end thereof as described above with respectA to the prior art. However, withthis novel connecting member construction of my invention, dangerous stress Aconcentrations exist in the plates ID and I I immediately adjacent the ends of the connecting member I4 and, to overcome this unsatisfactorycondition, I provide the pads and I6 which eiectivelyv reinforceY the respective plates in their otherwise dangerous zones.

By the present invention, then, the pads I5 and I- prevent undue flexing of the plate members` l0 and ll with` the result that thereis obtained a more eiicient and reliable juncture-between the connecting member I4 and said. plate members Il), Il. l1

It shall be understood that my invention is applicable to various vforms or types of hollow propeller blades and that it is not to be restricted to a propeller blade formed from two plates. Thus, the plates referred to in the claims may be formed from a single piece of material. vThey need not be separate plates joined together at their edges as illustrated. Alternativelyour or more plates may be utilizedto form the propeller blade.

It shall be understood that my invention, in broad aspects thereof, is applicable to propeller blades wherein the member I4 is formed integrally with one, both or all of the blade-forming plates.

While the invention has been described with respect to a certain particular preferred example which gives satisfactory results, it will be understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing so 'i the rib plane.

d from the spirit and scope of the invention and it is intended therefore in the appended claims to cover all such changes and modifications.

V.What is claimed as new and desired to be secured by Letters Patent is:

` 1. In a propeller, a pair of plates disposed in facing relation to form a propeller blade, an integral longitudinally extending rib formed on each of said plates, a taperedv connecting member between and joining said ribs, said connecting member` having a concavely curved recess formed in the `wide end thereof, a section-thickening pad formed on each of said plates bordering and underlying the recessed end of said connecting member, the curved ends of said recess blending into the surfaces of said pads, and a recessdefining edge of said connecting member substantially thicker than the rest of said connect- -ing member.

2. In ahollow propeller blade comprising flattened thrust and camber plates orV blade vplanform constituting an airfoil portion, a cylindrical shank portion, a transition portion blending the shank portion into the airfoil portion and a substantially flat rib bridging said thrust and camber plates and extending longitudinally of the blade. from a point near the tip to an inner rib end in said transition portion, tho-se improvements which consist in integral pad portions on the thrust and camber plates in the area underlying and bordering the inner rib ends, the thickness of each plate and pad together being greater than the thickness of the plate surrounding the pads, said rib end being concavely curved, the curve thereof defining cusp portions blending into said pad portions.

3. In a hollow propeller blade comprising nattened thrust and camber plates of blade planform constituting an airfoil portion, a cylindrical shank portion, a transition portion blending the shankportion into the airfoil portion and a substantially at rib bridging said thrust and camber -plates and extending longitudinally of the blade from a point near the tip to an inner rib end in said transition portion, those improvements which consist in integral pad portions on the thrust andY camber plates in the area underlying and bordering the inner rib ends, the thickness of each plate and pad together being greater than the thickness of the plate surrounding the pads, said ribend being concavely curved, the curve thereof deiining cusp portions blending into said pad portions, and sections on the central por- 'tion of thefconcavely curved rib end Awhich are materially thicker than the rib proper, the thickened section being symmetrical on both sidesV of Y GEORGE w. BRADY.

lmrrnaENcits CITED The following references are of record in the -rlle of this patent: A

UNITED STATES PATEN'ISI Pavlecka Nov. 2, 1937 

